A flexible process for the production of an antibacterial cationic dyeable polyester fiber

Abstract

The application discloses a flexible preparation method of antibacterial cationic dyeable polyester fiber, and belongs to the technical field of polyester material and fiber preparation. The method is characterized in that: a high-esterification-rate esterification product is obtained through esterification reaction of terephthalic acid and a dihydric alcohol; a pretreated cationic dyeable third monomer is introduced after esterification; uniform embedding of the third monomer and stable melt structure are realized through normal-pressure homogenization and segmented gradient polycondensation by reducing temperature; a compounded antibacterial powder is added on line in the melt conveying stage after the completion of polycondensation; a three-stage dispersion mode of pre-homogenization-high-shear dispersion-low-shear homogenization is adopted to realize efficient dispersion of the antibacterial component without interfering with the polymerization process; and polyester fiber with dyeability and antibacterial property is obtained through spinning forming. The method effectively solves the problems of easy self-polymerization of the third monomer and uneven dispersion of the antibacterial powder, and the obtained fiber is uniform in dyeing, stable in antibacterial performance and good in mechanical property, and is suitable for continuous production.

Description

Technical Field

[0001] This invention relates to the field of polyester materials and fiber preparation technology, specifically to a flexible preparation method for polyester fibers dyeable with antibacterial cationic dyes. Background Technology

[0002] Polyester fiber, due to its stable mechanical properties, abrasion and wrinkle resistance, excellent dimensional stability, and suitability for large-scale continuous processing, has become one of the most widely used synthetic fibers. As textiles develop towards functionalization, differentiation, and high-end products, the industry has placed higher demands on the dyeing adaptability, functionality, and production process stability of polyester fibers. Especially in the dyeing and finishing process, how to improve the adaptability of polyester materials to specific dye systems and endow them with additional functions while maintaining their original processing and mechanical properties has become an important research direction for polyester material modification.

[0003] In conventional polyester materials, due to their dense molecular structure and low content of polar groups, their affinity for some dye systems is insufficient, often requiring higher dyeing temperatures or complex process conditions to achieve ideal dyeing results. To improve this, existing technologies typically introduce a third monomer containing ionic or strongly polar groups during polyester polymerization, forming structural units in the polyester molecular chain that can interact with dye molecules, thereby enhancing the affinity for dye systems. However, in practical applications, the above modification methods still have many shortcomings. On the one hand, improper timing of the introduction of the third monomer, often added before the esterification reaction is fully completed, easily leads to local enrichment of ionic groups, initiating self-polymerization or ion association, forming microgels or insoluble aggregates, resulting in uneven melt structure and affecting subsequent spinning stability, manifesting as easy clogging of melt filters, increased breakage rate during spinning, and uneven fiber evenness. On the other hand, the introduction of antibacterial functional additives also has significant drawbacks. In existing technologies, antibacterial powders are often added directly during the polymerization stage. This can lead to interactions between the antibacterial agent and the catalytic system of polyester synthesis, interfering with esterification and polycondensation reactions, and affecting the polyester synthesis process and the molecular weight and distribution of the products. Furthermore, due to poor interfacial compatibility between the powder and the polyester melt, and the lack of effective dispersion methods, agglomeration is likely to occur, resulting in uneven distribution of antibacterial properties and exacerbating melt rheological fluctuations. In addition, achieving antibacterial modification through blending with functional masterbatches requires multiple melt processing steps, increasing the material's thermal history, which can easily lead to polyester degradation, reduce fiber mechanical properties, and increase production costs.

[0004] Meanwhile, existing technologies lack systematic optimization in parameter control during polymerization and melt processing, especially in terms of polycondensation conditions after the introduction of the third monomer and melt mixing methods. They often employ a single shear mode, making it difficult to balance powder dispersion uniformity and melt rheological stability, resulting in significant fluctuations in melt pressure and flow rate, which is detrimental to continuous and stable production. Furthermore, current research largely focuses on single-functional modification, with insufficient synergistic regulation of cationic dyeability and antibacterial properties, making it difficult to simultaneously achieve comprehensive improvements in dyeing uniformity, antibacterial durability, and processing stability.

[0005] In summary, how to achieve stable polymerization, uniform embedding of the third monomer, efficient dispersion of antibacterial powder, and controllable melt rheology in the continuous polyester preparation process, so as to ensure mechanical properties and processing stability while taking into account the dyeability of cationic dyes and long-lasting antibacterial properties, has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to solve the problems of uneven distribution of the third monomer, poor dispersibility of antibacterial powder, and insufficient melt stability in the preparation of polyester fibers, and to provide a flexible preparation method for polyester fibers dyeable with antibacterial cationic dyes.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing flexible polyester fibers dyeable with antibacterial cationic dyes includes the following steps: S1: Preparation of polyester esterification reaction products Terephthalic acid and diol are mixed in a molar ratio of 1:(1.05~1.6) to form a slurry, and an esterification reaction is carried out. The esterification reaction temperature is controlled at 230~260℃ until the esterification rate is ≥90% (preferably 90%~95%), and then the esterification reaction is terminated to obtain the polyester esterification reaction product. The diol is selected from one or more of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0008] S2: Preparation of the third monomer solution A third monomer solution is prepared by transesterification of isophthalic acid-5-sulfonate with a diol, controlling the transesterification rate to be 75-90% (preferably 80%-88%). The mass concentration of the third monomer solution is 20-40%, and before adding the polyester esterification reaction product, it is subjected to precision filtration to remove particles with a particle size greater than 5 μm. The third monomer is one or more of ethylene glycol 5-sulfonate sodium isophthalate, ethylene glycol 5-sulfonate potassium isophthalate, propylene glycol 5-sulfonate sodium isophthalate, propylene glycol 5-sulfonate potassium isophthalate, butylene glycol 5-sulfonate sodium isophthalate, or butylene glycol 5-sulfonate potassium isophthalate.

[0009] S3: Synthesis of cationic dyeable copolyester esters The polyester esterification reaction product obtained by S1 is cooled to 230~240℃ (this temperature is 5~25℃ lower than the esterification termination temperature), and the third monomer solution, ether inhibitor, stabilizer and polyester catalyst are added respectively. After dynamic mixing, the reaction is carried out under normal pressure for 20~45 min to obtain cationic dyeable copolyester esterification. Based on 100 parts by weight of the antibacterial cationic dyeable copolyester, the amount of the third monomer (on a dry basis) added is 1-3 parts by weight; the ether inhibitor is added at 0.5-2.5% of the amount of the third monomer added, and the stabilizer and polyester catalyst are added at 80-600 ppm and 150-400 ppm of the copolyester, respectively; the ether inhibitor includes one or a mixture of sodium acetate, potassium acetate, calcium acetate, and zinc acetate, the stabilizer is selected from one or more of trimethyl phosphate, phosphoric acid, and triphenyl phosphite, and the polyester catalyst is selected from one or more of antimony glycolate, antimony trioxide, antimony acetate, stannous oxide, zinc oxide, and tetrabutyl titanate.

[0010] S4: Segmented gradient polycondensation reaction Cationic dyeable copolyester esters were subjected to pre-condensation and final condensation reactions to obtain cationic dyeable copolyester melts. The pre-condensation stage primarily involved "low-temperature homogenization and slow viscosity increase," allowing the sulfonic acid-containing segments to diffuse fully before the molecular weight significantly increased, thus avoiding localized ion enrichment. The final condensation stage primarily involved "high-temperature setting and rapid viscosity increase," achieving a stable increase in molecular weight while suppressing thermosensitive side reactions and ensuring stable melt rheological properties. This approach solves problems such as uneven molecular weight distribution and large melt viscosity fluctuations in existing condensation processes.

[0011] Option 1 (Preferred Option): The pre-polymerization reaction is carried out in two stages. The reaction pressure of the first stage of pre-polymerization is 5~15 kPa, the temperature is 250~260℃, and the reaction time is 20~30 min. The reaction pressure of the second stage of pre-polymerization is 0.5~2 kPa, the temperature is 255~270℃, and the reaction time is 25~40 min. The reaction temperature of the final polycondensation reaction is 260~285℃, the reaction pressure is 0.05~0.15 kPa, and the reaction time is 100~180 min. Option 2: The reaction temperature of the pre-condensation reaction is 250~270℃, the reaction pressure is reduced from the atmospheric pressure at the later stage of esterification to -100kPa, and the reaction time is 30~60min; the reaction temperature of the final condensation reaction is 260~285℃, the reaction pressure is 0.05~0.15kPa, and the reaction time is 50~110min.

[0012] This innovative step employs a segmented gradient polycondensation design, which differs from the single polycondensation condition used in existing technologies. The segmented gradient polycondensation design divides the polycondensation reaction into multiple stages, with the reaction conditions for each stage optimized according to different objectives, equipment conditions, and requirements, thereby effectively improving the performance of the final product.

[0013] S5: Antibacterial functional powder pretreatment The antibacterial functional powder is a compound system comprising, by weight: 100 parts antibacterial component, 2-10 parts dispersing and synergistic component, 0.3-4 parts interfacial compatibility component, and 0.1-1.0 parts antibacterial enhancer; the antibacterial component is selected from one or more of silver-loaded antibacterial agents, zinc-loaded antibacterial agents, and copper-loaded antibacterial agents; the dispersing and synergistic component is selected from one or more of polyethylene wax, polyvinylpyrrolidone, sodium polyacrylate, and sodium hexametaphosphate; the interfacial compatibility component is selected from one or more of ethylene bis-stearamide, fatty acid polyethylene glycol ester, polyether-modified silicone oil, and quaternized organosilicon; and the antibacterial enhancer is selected from one or more of nano-silica, titanium dioxide, zinc oxide, and montmorillonite.

[0014] The antibacterial functional powder compound system needs to be pre-treated by ultrasonic-microwave linkage and vacuum filtration before being added to the cationic polyester melt. The pretreatment conditions are: ultrasonic power 250W, microwave power 180W, temperature 60-70℃, reaction time 60-90min, with high-speed stirring (800-1000r / min) to ensure the modified system is uniformly coated on the powder surface, forming a composite modified layer with controllable thickness (5-10nm). The vacuum filtration conditions for the antibacterial compound system are: vacuum drying at 90-110℃ for 4-5h, followed by airflow milling at a pressure of 0.3-0.5MPa to ensure the powder particle size is maintained at 200-700nm, finally obtaining the pre-treated antibacterial functional powder.

[0015] S6: Online flexible dispersion and melt stabilization of antibacterial functional powders The cationic dyeable copolyester melt is filtered through a melt filter and then transported through a pipeline. During transport, an antibacterial functional powder compound system is introduced. The melt undergoes a three-stage treatment process—pre-homogenization, high-shear dispersion, and low-shear homogenization—along with stable pressure metering output, to obtain a uniformly dispersed and flowable antibacterial cationic dyeable polyester melt. The antibacterial functional powder compound system is added at a rate of 4000~10000ppm (preferably 5000~8000ppm) based on the mass of the cationic dyeable copolyester. The specific process of the three-stage mixing is as follows: A1: Pre-homogenization: Under the condition of a shear rate of 5~70s⁻¹, the antibacterial functional powder and the cationic dyeable copolyester melt are subjected to a pre-homogenization treatment for 10~60s, so that the antibacterial functional powder is initially dispersed in the melt, and the melt temperature fluctuation during this process does not exceed 3℃. A2: High shear dispersion: Subsequently, the preliminary dispersion system is dispersed for 5 to 50 seconds under a shear rate of 300 to 1800 s⁻¹ to break up the hard agglomerates of the antibacterial functional powder, and the melt temperature rise during this process does not exceed 8°C. A3: Low-shear homogenization and pressure stabilization: Under low-shear turbulent conditions with a shear rate of 50~240s⁻¹, the dispersed melt is homogenized for 10~60s to control the melt pressure fluctuation within ±5%. After the above mixing is completed, the melt is subjected to stable pressure metering output, so that the output pressure fluctuation does not exceed 2% and the output flow fluctuation does not exceed 1.5%.

[0016] S7: Spinning and forming The above-mentioned antibacterial cationic dyeable polyester melt is subjected to metering, distribution and spinneret extrusion, cooling, oiling, networking and winding processes to obtain antibacterial cationic dyeable polyester fiber (which can be prepared in various specifications such as POY, FDY and short fiber).

[0017] The preferred spinning process parameters are: spinning temperature 260~283℃, filament cooling temperature 20~24℃, oiling rate 0.45~1.1%, network pressure 0.3~0.5MPa, spinning speed 2500~3800m / min (2500~3100m / min for POY, 2900~3800m / min for FDY), and overfeed rate 1.0~5.0%. If FDY is to be prepared, a stretching and heat setting process needs to be added, with the first roller temperature 75~90℃ and the first roller speed 1100~1900m / min, and the second roller temperature 110~140℃ and the second roller speed 3500~4000m / min.

[0018] Furthermore, the particle size of the antibacterial functional powder is controlled at 450~500nm to further improve its dispersibility in the melt and avoid spinning defects caused by large particles. Furthermore, in step S3, a dynamic mixer is used for mixing at a speed of 300-500 r / min to ensure that the third monomer solution and the polyester esterification reaction product are mixed evenly and to avoid local concentration differences.

[0019] The present invention, by adopting the above technical solution, has the following beneficial effects: (1) By introducing a third monomer solution that has been precisely filtered after the esterification reaction has reached a high degree of conversion, and carrying out the reaction at atmospheric pressure in a relatively mild temperature range, the third monomer is in a controlled active state when it enters the system. It can fully diffuse in the molten polyester system and gradually participate in the chain segment reaction, thereby making the distribution of sulfonic acid group-containing structural units in the molecular chain more uniform, reducing the possibility of local ion enrichment and condensation structure formation, and improving the structural uniformity and melt stability of the polyester system. (2) By constructing a segmented gradient polycondensation process, a time window for structural homogenization and chain segment rearrangement is provided in the pre-polycondensation stage, and the molecular weight is stably increased and the structure is fixed in the final polycondensation stage. This allows the ionic structure to complete the transition from a dispersed state to a stable embedded state during the molecular weight increase process, thereby reducing the amplification effect of the ionic structure on the rheological behavior of the melt, making the melt viscosity change more gradual, and improving the stability of the melt in the continuous processing process. (3) By compounding and surface treating the antibacterial functional powder, the antibacterial component, the dispersing synergistic component, the interfacial compatible component and the antibacterial reinforcing agent form a stable structure at the microscale. On the one hand, it promotes the wetting and dispersion of the antibacterial powder in the melt, and on the other hand, it enhances the interfacial interaction between the powder and the polyester macromolecule. At the same time, by regulating the release behavior of antibacterial ions through the reinforcing component, the antibacterial function exhibits a more stable and lasting release characteristic during the use of the fiber, and reduces the tendency of the powder to agglomerate in the melt. (4) By separating the introduction of antibacterial functional powder from the polymerization reaction process in the process path, and adopting a multi-stage dispersion method consisting of low shear pre-dispersion, high shear depolymerization and low shear homogenization in the melt conveying stage, the antibacterial powder undergoes a process of gradual dispersion and structural stabilization in the melt. While achieving uniform distribution of powder, the temperature rise and pressure fluctuation of the melt are controlled, thereby ensuring the continuous stability of the melt conveying and spinning process. (5) Through the above-mentioned multi-dimensional synergistic regulation, the resulting polyester fiber can form a coordinated relationship between dyeing performance, antibacterial performance and mechanical properties. It can achieve uniform dyeing of cationic dyes, ensure the long-lasting and stable release of antibacterial functionality, and maintain the rheological stability and forming consistency of the fiber during processing, thereby meeting the requirements for multi-performance synergy under continuous production conditions. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow for the preparation method of flexible polyester fibers dyeable with antibacterial cationic dyes according to the present invention. Detailed Implementation

[0021] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0022] Unless otherwise defined, all scientific and technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art.

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] The following describes specific embodiments and... Figure 1 The invention is described in detail below, and these embodiments are for understanding rather than limiting the invention.

[0026] Example 1: Refer to Figure 1 This embodiment discloses a method for preparing flexible polyester fibers dyeable with antibacterial cationic dyes, as detailed below: Preparation of S1 polyester esterification reaction product: Terephthalic acid and ethylene glycol slurry were mixed in a molar ratio of 1:1.18 and then subjected to esterification reaction. The esterification reaction temperature was controlled at 248℃. When the esterification rate reached 90%, the esterification reaction was terminated to obtain the polyester esterification reaction product. Preparation of S2 third monomer solution: Sodium isophthalic acid-5-sulfonate was subjected to transesterification reaction with ethylene glycol at a molar ratio of 1:10, while sodium acetate was added to obtain an ethylene glycol solution of sodium isophthalic acid-5-sulfonate (SIPE) with a concentration of 33% and a transesterification rate of 83%. This solution was filtered through a precision filter (to remove particles with a particle size > 5 μm) and used as the third monomer. Synthesis of S3 cationic dyeable copolyester esterified product: The third monomer, sodium acetate, trimethyl phosphate, and antimony glycolate were added to the polyester esterification reaction product. The system temperature was 230℃ during the addition. After the materials were mixed evenly in a dynamic mixer (400 r / min), the reaction was carried out at atmospheric pressure for 30 min to obtain the cationic dyeable copolyester esterified product. Among them, the third monomer (dry basis) was added at 2% of the weight of the copolyester, sodium acetate was added at 1.5% of the amount of the third monomer added, and trimethyl phosphate and antimony glycolate were added at 300 ppm and 250 ppm of the copolyester, respectively. S4 segmented gradient polycondensation reaction: The cationic dyeable copolyester ester is subjected to pre-polymerization and final polycondensation reactions in sequence; the first stage of pre-polymerization is carried out at a temperature of 255℃, a pressure of 10kPa, and a reaction time of 25min; the second stage of pre-polymerization is carried out at a temperature of 260℃, a pressure of 1kPa, and a reaction time of 40min; the final polycondensation is carried out at a temperature of 280℃, a pressure of 0.1kPa, and a reaction time of 100min. When the intrinsic viscosity of the copolyester reaches 0.58dL / g, the final polycondensation is terminated to obtain the cationic dyeable copolyester melt. S5 Antibacterial Functional Powder Pretreatment: Antibacterial component zinc oxide powder, dispersing synergistic component polyethylene wax, interfacial compatibility component ethylene bis-stearamide, and antibacterial reinforcing agent nano-silica are dried and premixed in a ratio of 100:5:0.5:0.4. The mixture is then subjected to ultrasonic-microwave combined treatment and vacuum filtration to obtain an antibacterial functional compound system with a particle size of approximately 450 nm. The pretreatment conditions are: ultrasonic power 250 W, microwave power 180 W, temperature 70℃, reaction time 65 min, and high-speed stirring speed 900 r / min, ensuring that the modified system uniformly coats the powder surface, forming a composite modified layer approximately 7 nm thick. Vacuum drying at 100℃ for 4.5 h is followed by airflow milling at a pressure of 0.5 MPa to ensure the powder particle size is maintained at approximately 450 nm.

[0027] Online flexible dispersion and melt pressure stabilization of S6 antibacterial functional powder: The cationic dyeable copolyester melt is filtered through a high-precision melt filter and then transported through pipelines. The antibacterial functional powder compound system is then fed into the melt via a screw pump, with the antibacterial functional powder added at 5000 ppm by weight of the copolyester. Subsequently, the antibacterial compound powder system and the copolyester melt undergo a three-stage mixing process: A1: Shear rate 50s -1 Pre-homogenize for 30 seconds, with temperature fluctuations within ±3℃; A2: Shear rate 1500s -1 High shear dispersion for 35 seconds breaks down hard agglomerates of antibacterial functional powders, and the melt temperature rise is ≤8℃; A3: Shear rate 200s -1 Low shear homogenization for 25 seconds, melt pressure fluctuation within ±5%; After further extrusion and pressure stabilization by the melt gear pump, the melt pressure fluctuation at the output end is within ±2%, and the flow fluctuation is within ±1.5%, resulting in a uniformly dispersed and stable antibacterial cationic dyeable polyester melt. S7 Spinning Forming: The above melt is metered, distributed, extruded through a spinneret, cooled, oiled, networked, and wound to produce antibacterial cationic dyeable polyester pre-oriented yarn POY 120dtex / 48f. The spinning process parameters are as follows: spinning temperature 279℃, yarn cooling temperature 24℃, oiling rate 0.45%, network pressure 0.5MPa, spinning speed 3150m / min, overfeed rate 1.2%, and yarn winding tension 11.8cN.

[0028] Performance testing: breaking strength 1.82 cN / dtex, breaking elongation 135%, yarn unevenness 0.99%; uniform dyeing and good coloring; inhibition rate of Staphylococcus aureus 92%, Escherichia coli 95%, and Candida albicans 89%; melt pressure fluctuation within ±2.0%; melt filter service life 25-30 days; component service life approximately 15 days; few spinning ends; product quality rate over 90%.

[0029] Example 2: The difference between this example and Example 1 is that the third monomer solution is an ethylene glycol solution of potassium isophthalate-5-sulfonate, the polycondensation process adopts Scheme 2, and the spinning stage adds stretching, heat setting and other processes to prepare antibacterial cationic dyeable polyester FDY, as detailed below: Preparation of S1 polyester esterification reaction product: Terephthalic acid and ethylene glycol slurry were mixed in a molar ratio of 1:1.25 and then subjected to esterification reaction at a temperature of 245℃. The reaction was terminated when the esterification rate was 92%. S2 third monomer solution preparation: potassium isophthalate-5-sulfonate reacts with ethylene glycol for transesterification, solution concentration 30%, transesterification rate 88%, filter and set aside. Synthesis of S3 cationic dyeable copolyester esterified product: The temperature of the above polyester esterification reaction product system was lowered to 235℃, the third monomer (dry basis) was added at 1.5% of the weight of the copolyester, zinc acetate was added at 1.3% of the amount of the third monomer added, phosphoric acid and antimony trioxide were added at 350ppm and 200ppm of the copolyester, respectively, and the reaction was carried out at atmospheric pressure for 30min. S4 segmented gradient polycondensation reaction: pre-polymerization temperature 260℃, reaction pressure from atmospheric pressure to -100kPa, reaction time 45min; final polycondensation temperature 278℃, pressure 0.07kPa, reaction time 100min, reaction terminated when intrinsic viscosity reaches 0.60dL / g. Pretreatment and flexible dispersion and pressure stabilization of S5 and S6 antibacterial functional powders: The antibacterial functional powders include silver-loaded antibacterial agent (particle size 500nm), polyvinylpyrrolidone, fatty acid polyethylene glycol ester, and nano zinc oxide (particle size 20-80nm), premixed in a ratio of 100:8:0.5:0.3. After ultrasonic and microwave combined treatment and vacuum filtration, cationic dyeable copolyester melt is added. The antibacterial functional powder addition amount is 5800ppm. The ultrasonic power is 250W, the microwave power is 180W, the temperature is 65℃, the reaction time is 80min, and the high-speed stirring speed is 900r / min to ensure that the modified system uniformly coats the powder surface, forming a composite modified layer approximately 6nm thick. Then, it is vacuum dried at 95℃ for 5h, followed by air jet milling at a pressure of 0.4MPa to ensure that the powder particle size is maintained at around 500nm. Three-stage mixing parameters: A1: Shear rate 60s -1 Pre-homogenize for 32 seconds, melt temperature fluctuation ≤2.5%; A2: Shear rate 1600s -1 High-shear dispersion melt temperature rise ≤7.0% after 36 seconds; A3: Shear rate 220s -1 Homogenize for 25 seconds; after shearing and pressure stabilization by gear pump, the melt pressure fluctuation is within ±2.0%, and the flow rate fluctuation is within ±1.3%. S7 spinning process: spinning temperature 280℃, cooling air temperature 20℃, network pressure 0.3MPa, winding speed 3800m / min, first roller temperature 80℃, first roller speed 1560m / min, second roller temperature 125℃, second roller speed 3970m / min, to produce FDY83dtex / 36f.

[0030] Performance testing: Tensile strength 3.5 cN / dtex, elongation at break 32.5%, network density 11 cells / m, oil content 1.0%; uniform dyeing and excellent coloring; antibacterial rate against Staphylococcus aureus 98%, Escherichia coli 96%, and Candida albicans 95%; melt filter service life 25-30 days, spinning assembly service life approximately 15 days, low yarn breakage, and product quality rate exceeding 87%.

[0031] Example 3: The difference between this example and Example 1 is that 1,3-propanediol is used as the diol, and the amount of antibacterial powder added is 6000 ppm, as detailed below: Preparation of S1 polyester esterification reaction product: terephthalic acid to 1,3-propanediol molar ratio 1:1.6, esterification temperature 238℃, reaction terminated when esterification rate 95%; Preparation of S2 third monomer: potassium isophthalate-5-sulfonate reacts with 1,3-propanediol for transesterification, solution concentration 28%, transesterification rate 85%, filtered and set aside. Synthesis of S3 cationic dyeable copolyester ester: The system temperature was 230℃. The third monomer was added at 2.0% of the weight of the copolyester, along with 2.0% of polyethylene glycol (PEG). Sodium acetate was added at 1.5% of the amount of the third monomer. Triphenyl phosphite and tetrabutyl polyester titanate were added at 220ppm and 200ppm of the copolyester, respectively. The reaction was carried out at atmospheric pressure for 30 min. S4 segmented gradient polycondensation reaction: Pre-polymerization stage 1: temperature 252℃, pressure 10kPa, reaction time 20min; Pre-polymerization stage 2: temperature 258℃, pressure 1kPa, reaction time 20min; Final polycondensation temperature 265℃, pressure 0.06kPa, reaction time 80min, reaction is terminated when intrinsic viscosity reaches 0.95dL / g. S5 and S6 antibacterial functional powder pretreatment, flexible dispersion, and pressure stabilization: The antibacterial functional powder consists of zinc oxide (450nm), sodium polyacrylate, ethylene bis-stearamide, and nano-titanium dioxide (particle size 10-50nm), premixed at a ratio of 100:6:0.6:0.3, with an addition amount of 6000ppm; three-stage mixing parameters: A1: Shear rate 55s -1 Pre-homogenize for 22 seconds; A2: Shear rate 1400s -1 High shear dispersion for 30 seconds; A3: Shear rate 200s -1 Homogenize for 30 seconds; after further shearing and pressure stabilization metering, the melt pressure fluctuation is within ±2.0%, and the flow rate fluctuation is within ±1.5%. S7 spinning process: spinning temperature 258℃, cooling air velocity 0.4m / s, spinning speed 2600m / min, to produce POY.

[0032] Performance testing: Tensile strength 2.0 cN / dtex, elongation at break 95%, yarn evenness 1.3%, oil content 1.1%; uniform dyeing and good coloring; antibacterial rate against Staphylococcus aureus 98.5%, Escherichia coli 99.0%, and Candida albicans 96.8%; melt filter service life 24-29 days, component service life approximately 14 days, low yarn breakage, and product quality rate exceeding 86%.

[0033] The only difference between Examples 4-7 and Example 1 is the single variable, as detailed below: Example 4: The concentration of the third monomer solution was 20%, the transesterification rate was 88%, and the reaction in step S3 was carried out at atmospheric pressure for 30 min; Example 5: The concentration of the third monomer solution was 40%, the transesterification rate was 82%, the temperature of the S3 step system was 235℃, and the reaction was carried out at atmospheric pressure for 40 min; Example 6: The system temperature in step S3 was 240°C; Example 7: Antibacterial functional powder addition amount 10000ppm.

[0034] The performance tests of the pre-oriented yarns obtained in Examples 4-7 above are as follows: breaking strength 1.76-1.85 cN / dtex, breaking elongation 135-140%, yarn unevenness 0.98-1.5%; uniform dyeing and good coloring; antibacterial rate 86-100%; melt pressure fluctuation within ±2.0%; melt filter service life 25-30 days; component service life 12-15 days; and few yarn breaks during spinning.

[0035] Comparative Example 1: The third monomer was added when the esterification rate was 60% (added early), and the remaining steps were the same as in Example 1 to prepare pre-oriented yarn; Comparative Example 2: Antibacterial functional powder was added before pre-condensation (antibacterial agent was added during the polymerization stage), and the remaining steps were the same as in Example 1 to prepare pre-oriented yarn; Comparative Example 3: The antibacterial powder compound system was premixed and added directly to the system without ultrasonic and microwave linkage treatment. The remaining steps were the same as in Example 1 to prepare pre-oriented filaments. Comparative Example 4: Antibacterial powder mixing was performed using a single shear (800s) -1 (20s), without segmented shearing and voltage stabilization metering, the remaining steps are the same as in Example 1, to prepare pre-oriented yarn.

[0036] The performance test results of comparative examples 1 to 4 are as follows: Comparative Example 1: Tensile strength 1.6 cN / dtex, elongation at break 118%, yarn unevenness 2.8%; uneven dyeing, poor coloring; antibacterial rate 72~89%; melt pressure fluctuation ≥4.5%, melt filter service life 5~6 days, component service life about 6 days, many spinning ends broken, cationic dye dyeing test did not meet the standard requirements, and dyeing performance was poor; Comparative Example 2: Tensile strength 1.55 cN / dtex, elongation at break 120%, yarn unevenness 1.95%; uneven dyeing, poor coloring; antibacterial rate 60~82%; melt pressure fluctuation ≥4.0%, melt filter service life 7~9 days, component service life about 7 days, many spinning ends broken, cationic dye dyeing test did not meet the standard requirements, and dyeing uniformity was poor; Comparative Example 3: Tensile strength 1.52 cN / dtex, elongation at break 112%, yarn unevenness 3.25%; dyeing was significantly uneven with poor coloring; antibacterial rate 59~85%; melt pressure fluctuation ≥5.0%, melt filter service life 25~30 days, component service life about 5 days, spinning component pressure was prone to short-term spikes, many yarn breaks occurred, cationic dye dyeing test did not meet the standard requirements, and dyeing uniformity was poor; Comparative Example 4: Tensile strength 1.58 cN / dtex, elongation at break 117%, yarn unevenness 2.35%; dyeing was significantly uneven with poor coloring; antibacterial rate 45~76%; melt pressure fluctuation ≥5.0%, melt filter service life 25~30 days, component service life about 3 days, spinning component pressure was prone to short-term spikes, many yarn breaks occurred, cationic dye dyeing test did not meet the standard requirements, and dyeing uniformity was poor.

[0037] To systematically evaluate the comprehensive performance of the prepared polyester fibers in terms of mechanical properties, structural uniformity, dyeability, antibacterial properties, and melt processing stability, standardized tests were performed on the samples obtained in each example and comparative example. All performance tests were conducted under specified environmental conditions and using relevant national or industry standard methods to ensure the accuracy and comparability of the test results. Specific testing methods are as follows: (1) Mechanical properties: Tested according to GB / T 14344 "Test method for tensile properties of chemical fiber filaments", constant temperature 20±2℃, relative humidity 65±5%, conditioned for 24h, clamping distance 20mm, tensile speed 20mm / min, ≥20 monofilaments were tested and the average value was taken; (2) Evenness: According to GB / T 14346 "Test Method for Evenness of Chemical Fiber Filament", the evenness tester was used, and the sample length was ≥400m; (3) Cationic dyeability: The dyeing uniformity and degree of dyeing were qualitatively tested according to FZ / T 50020 "Test Method for Dyeing Rate of Modified Polyester Dyed by Cationic Dyes"; (4) Antibacterial properties: The inhibition rate against Staphylococcus aureus, Escherichia coli and Candida albicans was tested according to GB / T 20944.3 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method". (5) Melt processing stability: Record the usage cycle of melt filter and spinning assembly, melt pressure fluctuation (recorded in real time by online sensors), and spinning head breakage.

[0038] The test results are shown in Table 1.

[0039] Table 1 Test Results

[0040] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing flexible polyester fibers dyeable with antibacterial cationic dyes, characterized in that, Includes the following steps: S1: Terephthalic acid is esterified with a diol to obtain a polyester esterification product with an esterification rate of ≥90%. S2: The third monomer solution is prepared by transesterification reaction of isophthalic acid-5-sulfonate with diol, and the third monomer solution and auxiliary agent are added to the polyester esterification reaction product at 230-240℃. After mixing evenly, the reaction is carried out at normal pressure for 20-45 min to obtain cationic dyeable copolyester esterification. S3: The cationic dyeable copolyester ester is subjected to pre-condensation and final condensation reactions in sequence to obtain a cationic dyeable copolyester melt; S4: After filtration, the cationic dyeable copolyester melt is fed with an antibacterial functional compound system online during the melt transport process. After three-stage dispersion treatment and stable metering output, it is spun into antibacterial cationic dyeable polyester fiber.

2. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, In step S1, the molar ratio of terephthalic acid to diol is 1:(1.05-1.6), and the esterification reaction temperature is 230-260℃.

3. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The third monomer mentioned in step S2 is one or more of ethylene glycol isophthalate-5-sulfonate, propylene glycol isophthalate-5-sulfonate, or butylene glycol isophthalate-5-sulfonate, with an ester exchange rate of 75% to 90%.

4. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The mass concentration of the third monomer solution is 20-40%, and the amount of the third monomer (on a dry basis) added is 1-3 parts by mass based on 100 parts by mass of copolyester.

5. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, Before adding the third monomer solution, it is filtered to remove particles with a diameter greater than 5 μm.

6. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The pre-condensation reaction described in step S3 is carried out in two stages. The first stage of pre-condensation is carried out at a temperature of 250-260℃, a pressure of 5-15 kPa, and a time of 20-30 min. The second stage of pre-condensation is carried out at a temperature of 255-270℃, a pressure of 0.5-2 kPa, and a time of 25-40 min. The final condensation temperature is 260-285℃, a pressure of 0.05-0.15 kPa, and a time of 100-180 min.

7. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The antibacterial functional powder is a compound system, including antibacterial components, dispersing and synergistic components, interfacial compatibility components, and antibacterial enhancing components.

8. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 7, characterized in that, The antibacterial functional compound system needs to be pretreated before being added. The pretreatment includes ultrasonic and microwave combined treatment and vacuum drying treatment to make the powder particle size 200-700nm.

9. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The three-stage dispersion described in step S4 includes: Pre-homogenization treatment at a shear rate of 5 to 70 s -1 ; high shear dispersion, shear rate 300-1800 s -1 ; Low-shear homogenization, with shear rates ranging from 50 to 240 s⁻¹. -1 .

10. The method for preparing flexible antibacterial cationic dyeable polyester fibers according to claim 1, characterized in that, The amount of antibacterial functional powder added is 4000-10000 ppm, and after stabilizing and metering, the melt pressure fluctuation is controlled within ±2%, and the flow rate fluctuation is controlled within ±1.5%.

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